JPS6315790A - Heat-transfer printing sheet - Google Patents

Abstract

A thermal transfer printing sheet comprising a substrate having a coating comprising an anthraquinone dye of the formula:wherein R is C_1-6-alkyl, C_4-8-cycloalkyl or C_2-6-alkenyl;R' is C_1-8-alkyl or C_{2 6}-alkenyl;and R² is H or C_1-6-alkyl or C_2-6-alkenyl,and its use in the preparation of a printed image on a receiver sheet by selective heating of the transfer sheet, in accordance with a pattern information signal, while in contact with the receiver sheet.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to thermal transfer printing ('r'rp), especially dyeing,
'I'TP sheets with dye mixtures or dye mixtures.

In conventional thermal transfer printing, heat transferable dyes are applied to a sheet-like substrate in the form of an ink, usually containing a polymeric or resinous binder to bind the dye to the substrate to form a transfer sheet. Ru. This is then brought into contact with the material to be printed, the receiver sheet, and selectively heated in accordance with the pattern transfer signal, whereby dye from the selectively heated areas of the transfer sheet is transferred to the receiver sheet and the transfer sheet A pattern is formed thereon as a result of the pattern of heat applied to it.

One essential criterion in the field of TTP dyes is its thermal properties, its color brightness, its fastness properties such as light fastness, and its ease of application to the substrate in the production of transfer sheets. It is. For suitable operation, the dye should be transferred evenly in proportion to the heat applied to the TTP sheet, where the depth of tone on the receiver sheet is proportional to the heat applied and the coloring True shades of gray are achieved with the receptor sheet.

Tonal lightness is important to achieve a wide tonal range, such as having six primary dye tones: yellow, magenta and indigo. For this reason, anthraquinone dyes are suitable for use in the TTP process.

Generally it is free of water bathing and ionic groups and is therefore free of water bathing groups, as the dye should be sufficiently mobile to migrate from the transfer sheet to the receiver sheet at the temperatures used, between 200 and 400°C. and not readily soluble in aqueous or water-miscible media such as alkanols. A number of suitable dyes are also not readily soluble in the hydrocarbon solvents normally used in the printing industry and therefore receptive thereto. Although the dye is applied as a dispersion in a suitable bath, brighter, glossier and flatter final prints are achieved when the dye is applied onto the substrate from solution. In order to achieve the possibility of deep tones in the receiver sheet, it is desirable that the dye be readily soluble in the ink medium, especially in the case of anthraquinone dyes, which have a relatively low extinction coefficient. It is also important that the dye applied from the liquid to the transfer sheet is crystal resistant, so that it remains as an amorphous layer on the transfer sheet for some time.

Means for Solving the Problems According to a first aspect of the invention, the formula: where R is C-6-alkyl, 04-8-cycloalkyl or 02-6-alkenyl;
6-alkyl or C2-6-alkenyl; R2 is H or C1-6-alkyl or (C2-6-
A thermal transfer printing sheet comprising a substrate having a coating comprising an anthraquinone dye □ which is an alkenyl dye is provided. Preferably, the radical represented by R is branched alkyl, and more particularly '03-1S-alkyl; particularly suitable is iso-propyl.

Examples of other groups represented by R are 5ee-butyl, in-butyl, ! ~butyl, allyl, 9-propyl, 2-methylbutyl and cyclohexyl.

Advantageously, R2 is H and R1 is in the para position with respect to the amino bridging group. It is particularly suitable that R1 is methyl. Examples of other groups represented by R1 and R2 are ethyl5, D-propyl, zolobyl, heather-butyl, n
-butyl and D-hexyl.

3fiA and B are nonionic groups at that position, which are advantageously not later arranged to form intramolecular hydrogen bonds;
An acidic hydrogen atom is substituted with. Examples of suitable substituents are norodene, especially bromine and chlorine, alkyl, especially C0-6-alkyl, and especially hydroxy in the position adjacent to the 9, 'io-' carbonyl group of the anthraquinone nucleus.

Specific examples of suitable dyes of formula 1 for use in the present invention are set forth below: 1 -CH(CH3)2T)-CH2R3
-CH3p-CH3H 3-CH3m-CH3H 6-CH3p-(n-04Hg) H7-CH(C
H3)2 1)-(n-C4H9) H8-
CH(CH3)2p-CH3m-CH39-n-, C,
H13p-=CH5,, Hlo-C! H (CH3)
CH2CH3p-CH3R11-CH2CH-CH,,
p-CHI H12・-CH2CH2CH-(:
'H2H Formula l dye with good thermal properties, its color depth is such that true gray level sea bream of coloring is achieved.
It is precisely proportional to the amount of heat applied and produces a flat print on the receiver sheet.

The dyes of formula 1 have strong coloring properties and good solubility in a wide range of solvents, in particular these solvents are widely used and accepted in the printing industry, such as alkanols such as ethanol and butanol, toluene, etc. Aromatic hydrocarbons such as MEK, ketones and cyclohexanone such as MIBK.

This facilitates the application of dye from the layer liquid to the substrate and thus facilitates achieving bright, glossy prints on the receiver sheet. The combination of strong coloring properties and good solubility in suitable solvents allows the achievement of depth and even focus.

The substrate is capable of withstanding temperatures contained in TTP, up to 400°C, for periods of up to %o seconds (msec);
Nevertheless, the applied heat is transmitted through the dye on one side and on the other side, typically 1 to 10/1000
Advantageously, the sheet material may be thin enough to be transferred to the sheet within a short period of time, such as seconds. (8) of the preferred material.

Examples include paper, especially high-quality paper of uniform thickness such as capacitor paper, polyester, polyac, rylate, polyamide, cellulose and polyalkylene fills, copolymers and laminated films, especially polyacrylate,
It is in its metallized form that the ester layer runs a bonded laminate. A particularly suitable substrate consists of a laminate of a polyester layer sandwiched between two heat resistant layers of a polymer, such as a UV-cured acrylic resin. The acrylic resin is used to insulate the polyester from heat sources during printing and to inhibit diffusion of dye into the transfer sheet. The thickness of the substrate may vary within a wide range depending on its thermal properties, but preferably from below 50 μm, more preferably from 110 μm.
It is below μm.

The coating preferably consists of a binder and one or more dyes of formula I. The ratio of binder to dye is advantageously at least 1:1 to at least 10:11, in order to produce good adhesion between dye and substrate and no migration of the dye during storage. Even more advantageously 1.5:1. ~4:
It is 1. - The binder may be a resin or polymeric material suitable for bonding the dye to the substrate, which is soluble in the ink medium, ie in the medium the dye and binder are applied to the transfer sheet.

Examples of binders are ethyl hydroxyethyl cellulose (EHEC), hydroxypropyl cellulose (RP
C) cellulose derivatives such as ethylcellulose, methylcellulose, cellulose acetate and cellulose acetate butyrate; carbohydrate derivatives such as starch; alyanic acid derivatives; alkyd resins; vinyl resins and conductors such as; acrylates such as polyacrylic acid, polymethyl methacrylate and styrene-acrylate copolymers? Polymers and copolymers derived from acrylate derivatives and acrylate derivatives: polyester resin a1
Polyamide resins such as melamine; polyurea backbones and polyurethane resins; organosilicones such as polysiloxanes, epoxy resins and natural resins such as gum tragacanth and arabic yam.

However, it is customary to use binders that are readily soluble in one of the commercially available organic bath agents mentioned above. Suitable binders of this kind are particularly low and particularly low viscosity E
HEC, and ethyl cellulose.

The coating may also contain other additives such as hardeners, preservatives, etc., and these and other ingredients are more fully described in EP 133 011, EP 133 011;
No. 3012 and No. 111004.

According to other features of the invention, a transfer sheet coated with a dye of formula 1 is contacted with a receiver sheet, such that the dye is in contact with the receiver sheet, and selectively heating a portion of the transfer sheet; A method of transfer printing is thereby provided in which dyes in heated portions of the transfer sheet may be selectively transferred to a receiver sheet.

The receiver sheet advantageously has a copolyester surface coating into which the dye readily diffuses to facilitate transfer of the dye from the transfer sheet to the receiver sheet, advantageously suitable for photographic film. It is a white polyester paste.

The invention will be further described in detail in the following examples. All parts in the examples refer to weights not otherwise specified.

Example ink 1 20 g of cyclohexanone, 30 g of toluene and MEK
1-iso-zolopylamino-4-(4-
Prepare a solution of 3 g of methylphenylamino)-AQ and 30 g of a 20% solution of EHEC (low viscosity by %) in toluene.
After addition, the mixture was stirred for 5 minutes. The ink is stirred with gentle heating for an additional 60 minutes to effect complete dissolution of the solid components.

Ink 2 to Ink 8 The other seven inks were prepared by dissolving a sample of each of the dyes listed in Table 1 (all from Formula 1) in chloroform and dyeing 0.
．． Make a solution containing 45%, followed by a sufficient amount of E
It was prepared by dissolving HEC to give a binder level of 0.9% (dye:binder 1:2).

Table 1 1 1 -cH (cH3), 1) -CH2R
32-CH31)-CH2R 33-CH3m-CH3H 66-C! Ha p-(n-C4H9) H77
-CH(CH3)2p-(n-C!4Hg)
H88-CH(CH3)2-p-CH3m-CH3
EXAMPLE 1 A transfer sheet, hereafter referred to as 'I'8I, is applied to a 6 micron sheet of ink 1t-polyethylene terephthalate using a metal Mayer rod wrapped in wire to form a 2 micron layer of ink on the surface of the sheet. Manufactured by manufacturing. The ink was dried with hot air.

Examples 2 to 8 Other 7 types of transfer sheets according to the present invention, transfer sheets) T82
~'I'88 in place of ink 1, each ink 2~
7 according to the method of Example 1.

Example 9 A sample of Te3 was sandwiched with a receiver sheet having a composite structure, based on a white polyester base with a copolyester receiving surface, in contact with the printed surface of the former and the receiving surface of the latter. Make it.

A sand inch-like object is placed on the P ram of a thermal transfer printing device, and the temperature is selectively increased from 2 to 10μ8θC according to the pattern information signal.
The dye is passed from the thermal transfer sheet over a matrix of closely spaced pixels *(pixθl) heated to >600° C. while it is hot, at a location on the thermal transfer sheet where it contacts the pixels. Transfer to receptor sheet.

After passing over the row of pixels, the transfer sheet was separated from the receiver sheet. The printed receptor sheet is then R8
Apply as in 1.

*A pixel is an individual heating element of a heating head in a thermal transfer printing device.

Examples 10 to 16 The method of Example 9 was applied to each thermal transfer sheet (T82) instead of TSi.
Repeat with ~'I'88 and the printed receiver sheet then apply as R82-R8B.

Evaluation of Inks and Thermal Transfer & Receiver Sheets The stability of the ink and the quality of the prints on the thermal transfer sheets are evaluated by visual inspection and the quality of the brushes printed on the receiver sheets! 1 degree needle (SakuraDigital denslt
The color reflection density was evaluated using The results of the evaluation are listed in Table 2;

Claims (1)

[Claims] 1. Formula: ▲There are mathematical formulas, chemical formulas, tables, etc.▼ [In the formula, R is C_1_ to_6-alkyl, C_4_ to_8
-cycloalkyl or C_2_-_6-alkenyl, and R^1 is C_1_-_6-alkyl or C_2
_~_6-alkenyl, and R^2 is H or C_1_~_6-alkyl or C_
A thermal transfer printing sheet comprising a substrate having a coating comprising an anthraquinone dye of 2_ to_6-alkenyl. 2. The thermal transfer printing sheet according to claim 1, wherein R is branched C_3_-_6-alkyl. 3. The thermal transfer printing sheet according to claim 1, wherein R^1 is 4-methyl and R^2 is H. 4. Thermal transfer printing sheet according to claim 1, wherein the substrate has a coating consisting of the dye 1-i-propylamino-4-(4-methylphenylamino)-AQ. 5. A selective heating area on the opposite side of the thermal transfer sheet for contacting the receptor sheet such that the surface of the sheet with the dye is in contact with the receptor sheet and transferring the dye with the heated portion of the thermal transfer sheet. A thermal transfer printing sheet according to claim 1, wherein is selectively transferred to the receptor sheet.